Putin on Tuesday is to visit the Pope in the Vatican, the first time the two have met since Benedict succeeded the late Pope John Paul II in 2005. That meeting is likely to focus on the continued tensions between the Vatican and the Russian Orthodox Church, which have stood in the way of a papal visit to Russia.

The Russian church accuses Roman Catholics of improperly seeking converts in areas that traditionally would be Russian Orthodox. Relations between the churches have improved gradually over the past several years, but the Russian church's representative for European affairs was quoted Monday as saying that it was too early to talk of the Pope visiting.

A meeting of Benedict and Russian Orthodox Patriarch Alexy II would depend on "an understanding on key issues ... we first need to solve the existing problems," Bishop Hilarion was quoted as saying by the Interfax news agency.

Putin also is to meet Italian Prime Minister Romano Prodi. He then is scheduled to attend a Greece-Russia-Bulgaria summit in Athens. An agreement on constructing the Burgas-Alexandroupolis pipeline is to be signed during the summit, reports AP.

The pipeline, bypassing Turkey's cramped Bosporus Strait, would carry Russian oil from Burgas on Bulgaria's Black Sea coast to the Greek port of Alexandroupolis on the Mediterranean.

The Basmanny Court of Moscow arrested Michael Calvey, the founder of Baring Vostok investment fund, on allegations of embezzling 2.5 billion rubles from Vostochny Bank. Calvey will be held in custody until April 13